The present invention relates to a coupling device between two adjacent tubs of a scraper conveyor for mines, in which each tub comprises side members each having two superimposed lateral branches which are turned towards the inside and have between them an externally open longitudinal groove and which are arranged symmetrically relative to the vertical median plane of the tub, being joined together along a central longitudinal zone by a median plate and which have a preferably inverted M or sigma-shaped profile, said coupling device being of the type comprising a male connecting member integral with one of the ends of a side member, a female connecting member integral with the other end of the same side member, each of said connecting members being equipped with a retaining partition, a longitudinal slot and a lateral access opening issuing into the said slot, a connecting spindle having two abutment flanges and which can be inserted into or removed from the slots via the access openings of the said members when the latter are at least approximately aligned and brought adjacent with one another, a recess for one of the abutment flanges located to the rear of the corresponding retaining partition, as well as locking means for preventing the spindle from unexpectedly moving out of the slots of the said connecting members, whereby the flanges of the said spindle serve to bear against the corresponding retaining partition so as to permit the transmission of tensile stresses between two adjacent tubs, the male connecting member having a male guidance member or projecting portion which longitudinally projects beyond the corresponding side member and the female connecting member has a female guidance portion such as a connecting cavity serving to receive the said male member.
A coupling device of this type is known, for example, from French Pat. No. 2,016,116. In the case of the known device, the locking means act on the abutment flanges in such a way as to prevent their axially leaving their guidance recesses which retain and laterally guide the abutment flanges and which are only laterally accessible via the cylindrical spindle through the access openings, whose width is slightly larger than the diameter of the spindle and is equal to the diameter of the semi-cylindrical slot for the connecting spindle. Therefore, the cross-section of the connecting pin is relatively small compared with the overall dimensions of the coupling device. Moreover, the male connecting member of the known device has a transverse retaining partition which is located at the front end of the projecting portion. Thus, this arrangement also considerably limits the possibilities of transmitting high tensile stresses.
Another coupling device of approximately the same type as that mentioned hereinbefore is known, for example, from British Pat. No. 759,031 or French Pat. No. 1,114,925. In the case of this known device, the slots comprise cylindrical holes made in the connecting members and the joining member identical to the connecting spindle is constituted by a screw bolt and a nut, the bolt being threaded in the aligned slots of the corresponding connecting members, whereby the bolt head and the nut screwed onto the bolt after its longitudinal introduction into its two slots bear, if applicable, on the rear faces of the connecting members which surround the slots. The length of the joining member and more precisely the distance between the bolt head and the nut is generally sufficient to obtain a type of articulation between the two coupled tubs, said articulation leading to three degrees of freedom of movement in three directions starting from the theoretical centre of the coupling device, one of these directions being parallel to the conveyor travel direction and the two other directions are perpendicular to one another and to the said first direction.
The conveyor is displaced along the floor (wall) during a scraping operation or lateral displacement which comprises displacing the said conveyor in the direction perpendicular to the side members and parallel to the median plates of the tubs in sections, i.e. by several tubs, either immediately after the passage of the mining machine in the area of the section in question or after the return travel of the said machine.
During the scraping operations, the coupling devices between the tubs are very highly stressed. Thus, during the scraping of a subassembly or section of tubs, these devices are subject to high pressures and stresses and more particularly this applies to the coupling device connecting the final displaced tub to the first tub which has still not been displaced. The stresses acting on the different members of the coupling device are both longitudinal and transverse and are dependent on the force developed by the scraping jacks, the spacing between the said jacks, the slope and the weight of the conveyor.
The bolts and their threads, as joining members, are subjected to deformations which, even if they do not lead to a break, prevent any realignment and uncoupling between two adjacent tubs. The breakage of a coupling device leads, as is known, to incidents such as the rapid deterioration of the tub ends. The uncoupling of the tubs from one another, the breakage of movable equipment (pull chains and scrapers), etc.
Moreover, in the known coupling device, the fitting of a bolt, followed by the screwing of the nut onto the bolt and the locking of the nut are long and difficult operations.